Sickle cell disease (SCD) is an inherited hemoglobinopathy that leads to sickling of red blood cells and the development of chronic hemolytic anemia. SCD patients have lower risk for HIV-1 infection, but its underlying molecular mechanisms are not well understood. We recently showed that changes in iron metabolism leads to upregulation of innate immune response and prevent ex vivo HIV-1 infection of PBMCs obtained from SCD patients. Our working hypothesis is that hemolysis-mediated upregulation of ferroportin expression and iron export in SCD leads to the inhibition of HIV-1 replication. We further hypothesize that macrophage processing of abnormal sickle hemoglobin leads to interferon-? production and stimulation of antiviral response. What is yet unclear is whether SCD or sickle cell trait triggers an overall antiviral state or whether HIV-1 is controlled at post infection stage. To answer these questions, we will investigate HIV-1+ SCD patients and cohort of HIV-1+ sickle cell trait individuals to include males and Africans. We will also utilize mouse model of SCD to analyze EcoHIV-1 infection in vivo. In Specific Aim 1, we will analyze HIV-1 restriction in HIV-1+ SCD individuals. We will analyze the effect of SCD on HIV-1 infection in SCD HIV-1+ patients recruited from Howard University and Montefiore clinics. We will analyze their hematological and virological parameters and test host genes expression using RNA-Seq analysis. We will analyze their HIV-1 phylogeny, HLA-B alleles and inflammation markers. In Specific Aim 2, we will determine the effect of sickle cell trait on HIV-1 infection in African Americans and Africans and viral load in African Americans from WIHS, Multicenter Cohort AIDS Study (MACS), and a Nigerian cohort. We will conduct multivariable analysis to determine the effect of the trait on viral load, relationship to CD4/CD8 counts and levels of proteins involved in iron metabolism and HIV-1 restriction. We will also conduct a case control study to analyze HIV-1phylogeny and the effect of iron and inflammation markers on HIV-1 progression. In Specific Aim 3, we will analyze molecular mechanisms of HIV-1 inhibition in SCD and sickle cell trait. We will analyze expression of host HIV-1 restriction factors in monocyte- derived macrophages treated with HbSS and HbAS hemoglobin and test selected factors in ex vivo HIV-1 infection of PBMCs derived from SCD patients and HIV-1+ sickle cell trait participants from WIHS and MACS cohorts. We will also test HIV-1 infection in SCD and trait mouse models using EcoHIV virus that infects mice and leads to the latent HIV-1 infection in T cells and macrophages.The proposed research will elucidate the molecular mechanisms of HIV-1 inhibition in the settings of SCD and sickle cell trait, which could lead to novel anti-HIV-1 therapeutics based on the concept of HIV-1 restriction mediated by hemolysis and interferon induction by sickle cell hemoglobin.